1. Field of the Invention
The present invention relates to a seat device for supporting the cushion movable up and down to damp vibration.
2. Prior Art
When a seat is provided subject to vibration, it is well known that the cushion of this seat is supported movable up and down by a suspension means to damp the vibration.
It is common to the conventional techniques in this case that the whole of the cushion is supported elastically movable up and down, that the elastic force of an elastic member is balanced with the weight of a person seated and of the seat, and that the cushion is deformed when vibration is added.
In the case of this conventional seat device, however, most of the seat weight must be received by the elastic member. When the seat is installed in a small space, therefore, the elastic member used must have a large elastic or spring constant but this elastic member can serve only when vibration is substantially large. When the seat is used in a car, for example, it cannot serve as a truly comfortable seat which can damp even such vibration as caused by seams on the road.